The music mogul - who is expected to marry make-up artist Mezhgan Hussainy in early September - reportedly spent an hour looking at a luxury 1954 Jaguar XK convertible at a showroom in Los Angeles recently, and is thought to be buying the classic car for her 37th birthday.

A source said: "Money is clearly no object but he's considering buying her something that little bit special. He's obviously a big fan of cars but she is too."

The 'X Factor' judge - who is known for being vain - has already been splashing the cash on Mezhgan, as he recently bought her a joke his-and-hers diamond encrusted mirror for £7,000.

The source added to the Daily Mirror newspaper: "Simon also has a wicked sense of humour and decided to present her with a mirror so they could both check their reflections. It's a running joke between them."

The TV star is said to buy her romantic gifts almost every day, and recently treated Mezhgan to a "private Swedish massage".

A source said: "Red roses, French lingerie, Prada bags, you name it. He gives her something new practically every day. One particularly sweet surprise was private his-and-hers Swedish massages in their London hotel room."

The 50-year-old star is due to arrive back in the UK with Mezhgan later this month when he starts the new series of his TV talent show 'Britain's Got Talent'.